Numerous conversion systems have been developed over the years which convert analog signals to representative digital words. The coding schemes are many and varied and the steady progression takes advantage of the latest technological advances. Advances in integrated circuitry and related fabrication techniques give designers the necessary tools to achieve a good many goals which heretofore were only theoretically predicted. Switching times, memory capacities, bandwidths and a host of compilations and processes now are commonplace.
A system using the delta digitizing technique is one of the processes by which speech or similar analog signals are converted into a serial bit stream. Generally speaking, an analog-to-digital system creates digital words which represent the value of the original input analog signals. Unfortunately, wide dynamic excursions of the input analog signals cannot be responsively followed in the digital and analog conversions and information may be lost due to saturation of linear circuits. In addition, conventional displays and processing equipments may be unable to accommodate the additional bits of data that widely fluctuating analog signals create or might create. Numerous efforts have been attempted to accommodate the widely fluctuating signals and to compress their representative digital data signals.
The output from a spectrophotometer was hoped to be accommodated by a circuit arrangement diclosed by Adrian Frances Flynn et al in U.S. Patent and Trademark Office U.S. Pat. No. 3,995,265. In their approach, a comparison with an accumulation of a reference signal allowed processing of analog signals. This represents a meritorious advance in the state-of-the-art; however, it appears to be somewhat limited for it relies on a linear approach as opposed to a more accommodating, floating point conversion. William George Prowse discloses a modulator in a delta modulation system in his U.S. Patent and Trademark Office U.S. Pat. No. 4,110,705. The rapidly changing input voltages produced by high frequencies and/or large amplitudes are inadequately tracked between an accumulator value and an instantaneous analog signal input by a technique generally referred to as companding. In his system the effects of random or low level noise are reduced and modified step sizes are used to reduce the problems normally associated with the analog-to-digital and digital-to-analog conversions.
Thus, there is a continuing need in the state-of-the-art for an apparatus which can accommodate wide dynamic range analog input signals having a floating point decimal conversion to produce digital information in usable form by associated components such as readouts and microprocessors.